Datasheet

MC68HC908QB8 Data Sheet, Rev. 3
Freescale Semiconductor 109
Chapter 13
Enhanced Serial Communications Interface (ESCI) Module
13.1 Introduction
The enhanced serial communications interface (ESCI) module allows asynchronous communications
with peripheral devices and other microcontroller units (MCU).
The ESCI module shares its pins with general-purpose input/output (I/O) port pins. See Figure 13-1 for
port location of these shared pins. The ESCI baud rate clock source is controlled by a bit (ESCIBDSRC)
located in the configuration register.
13.2 Features
Features include:
• Full-duplex operation
• Standard mark/space non-return-to-zero (NRZ) format
• Programmable baud rates
• Programmable 8-bit or 9-bit character length
• Separately enabled transmitter and receiver
• Separate receiver and transmitter interrupt requests
• Programmable transmitter output polarity
• Receiver wakeup methods
– Idle line
– Address mark
• Interrupt-driven operation with eight interrupt flags:
– Transmitter empty
– Transmission complete
– Receiver full
– Idle receiver input
– Receiver overrun
– Noise error
– Framing error
– Parity error
• Receiver framing error detection
• Hardware parity checking
• 1/16 bit-time noise detection